1. Field of the Invention
The present invention relates to a position management system and a position management program, and more specifically, to a position management system and a position management program to detect a position and so on of each of a plurality of objects to be detected based on information from a tag which is provided to the object corresponding to characteristics of the object.
2. Description of the Related Art
Conventionally, there are various well-known technologies which use tags to detect positions of objects to be detected. For instance, in a technology described in JP2001-183455A, a plurality of ID tags are arranged in a floor face keeping predetermined spaces. In addition, an ID reader is attached to an object whose position is to be detected such as a mobile object or the like. Thus, the ID reader reads ID data from the plurality of ID tags to detect the position of the object to be detected.
Moreover, as a method to detect a position of an object to be detected, a method which analyzes camera images, a method which uses ultrasonic waves or infrared radiations, a method which uses RFID tags, and so on are generally employed.
However, the methods in the prior art cannot always specify a position of an object to be detected with high accuracy due to the following problems.
For instance, the technology described in JP2001-183455A can detect a two-dimensional position of an object to be detected but not a three-dimensional position of the object. Therefore, it is considered to be difficult to make a robot perform operations and movements which require detection of three-dimensional positions.
Moreover, in the method which analyzes camera images or the method which uses ultrasonic waves or infrared radiations, there is an occlusion problem. More specifically, when there is another object (an obstacle) other than an object to be detected between the object to be detected and a detector such as a camera, an ultrasonic detector, or an infrared detector, the detector cannot detect the position of the object to be detected which is placed behind the obstacle. Accordingly, none of the methods can always specify a position of an object to be detected with high accuracy.
In addition, detecting positions of a plurality of objects to be detected only using camera images causes not only increase in computational cost but also insufficient accuracy in detecting positions depending on photoenvironments such as lighting.
Moreover, as one of methods which analyze camera images, there is a well-known method which searches for a marker attached on an object to be detected in order to detect the position of the object. However, only by using the marker, the method generally cannot acquire specific information of the object to be detected such as a shape, a weight, and so on though the method can acquire the position of the object to be detected.
Meanwhile, in a position detection system which uses ultrasonic tags or infrared tags, the tags need to be powered from an external power supply. However, the tags might not be powered from an external power supply depending on sizes or positions in a detection space of the objects to which the tags are attached. In such cases, it is impossible to use the ultrasonic tags or the infrared tags. Therefore, it is impossible to detect positions of the tags. Furthermore, it is not appropriate to attach tags which need to be powered from an external power supply to objects which are frequently moved such as a glass, a chair, and a book.